Drones and Naval Warfare: Submarines
The Portuguese Navy has been around for more than 700 years, and for the first time since the days of the carrack, it is leading the world in ship design. The new ship carries the unlovely name of “Multifunctional Naval Platform,” but the illustrations in Seaforth’s World Naval Review 2025 reveal it looks like an aircraft carrier, with a flat deck, an island superstructure, and a ski-jump launch ramp for fixed-wing aircraft. It is small, frigate-sized, displacing about 7000 tons. And while it looks like an aircraft carrier, it is actually built for a specific type of aircraft. The MNP is the world’s first purpose-built drone carrier. And it costs only about $135 million, approximately one-hundredth of the price of a Ford-class American aircraft carrier.
What does this have to do with submarines? The MNP not only has a flight deck, it has a stern ramp, which, according to Seaforth’s World Naval Review, “will assist the operation of unmanned surface and unmanned underwater vehicles. The latter will include the Portuguese ROV Luso, which is capable of diving to depths of 6000 meters.”
In a previous column, I suggested that the proliferation of air and surface drones may create on the sea a situation long known in land warfare (since late 1914), “the emptiness of the battlefield.” The battlefield is empty because anything that can be seen will be killed. We are watching this play out at present in the Black Sea, where Ukrainian air and surface drones, along with anti-ship missiles, have driven the Russian Navy into port (and sometimes attacked it even there).
The implication of the Liso subsurface drone is that submarines may find themselves facing the same situation. In World War II, the aircraft carrier displaced the battleship as the capital ship, and then, in late April 1945, the submarine replaced the carrier when the first German Type XXI U-boat went to sea. Today, the submarine retains that role: no country can use a sea in which enemy submarines are operating.
Here is where it really gets interesting: if submarines find themselves facing multiple deadly underwater drones, does the subsurface ocean also become a place where the battlefield is empty? If so, does the submarine lose its role as the capital ship? What, if anything, replaces it? If nothing does, can anyone use the sea in wartime, and if so, how?
To be sure, proliferating underwater drones is not as easy and cheap as it is in the air. Drones too must be built to survive the vast pressure of the water as soon as they submerge. But with a non-nuclear attack submarine costing about $500 million and a nuclear submarine priced in billions, even relatively expensive underwater drones may be a good investment, especially in coastal waters and maritime chokepoints. If only one in one hundred underwater drones took out a Virginia-class nuclear attack submarine, those drones would pay a large return on a relatively small investment.
If underwater drones keep submarines in port while air and surface drones do the same for surface ships, no one will be able to use the sea in wartime, for military or commercial purposes. That would be a wholly new situation, one for which it is safe to say no defense ministry or navy is preparing. One direction in which it points is towards something I have written about before, building very large ships that can serve in both naval and commercial roles and can take multiple hits and keep going. Beyond that, I’m not sure I have any answers to the questions I have raised here. But I do know the questions are important.